This invention relates to pressure vessels.
More particularly, the invention concerns pressure vessels which can be used, for example, to keep a constant fluid pressure on the piston of a hydraulic cylinder.
It is known in the art to provide a pressure vessel with a passage having a valve therein which is operative to control fluid-flow through the passage. Usually, such a vessel is provided with an expandable elastic partition which subdivides the interior of the vessel into a gas-containing compartment and a liquid-containing compartment. An additional purpose of the valve is to prevent penetration of portions of the separating partition into the passage when the partition expands towards the passage during discharging of liquid from the vessel through the passage. It has been recognized that such pressure vessels are rather expensive to construct.
It is also known in the art to provide a pressure vessel with a separate liquid-discharging nipple which is connected, i.e., welded, to the vessel. Such a nipple is provided with a plurality of throughgoing passages of a small diameter. Thus, when the elastic partition expands, it cannot enter into the passage of the nipple. However, such a construction is also found to be relatively expensive.